Diabetes Drug, Metformin, Recalled for Cancer-Causing Contamination

Carolyn Casey, J.D.

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— Updated on July 30, 2020

Diabetes Drug, Metformin, Recalled for Cancer-Causing Contamination

On June 11, 2020, the FDA announced that five pharmaceutical companies would be voluntarily recalling certain extended-release metformin drugs (ERM) used in the treatment of type 2 diabetes. This announcement came two weeks following the FDA’s initial recall recommendation after agency testing of ERM revealed unacceptable levels of N-Nitrosodimethylamine (NDMA), a human carcinogen.

A Recurring Culprit: NDMA

The World Health Organization (WHO) classifies N-Nitrosodimethylamine (NDMA) as a probable human carcinogen.  N-nitrosamines, naturally occurring environmental toxins, generally form “when a secondary or tertiary amine reacts with a nitrosating agent.” Low levels of NDMA are found in roasted meats, cheese, beer, and other foods due to cooking and fermentation processes. As a carcinogen, NDMA has been associated with cancers of the liver, pancreas, kidney, bladder, stomach, colon, blood, and ovaries. NDMA has also been linked to non-Hodgkin’s lymphoma and multiple myeloma.

Metformin on the U.S. Market

Metformin is a prescription drug that aids high blood sugar regulation in patients with type 2 diabetes, a disease impacting 1 in 10 Americans. Metformin has been widely prescribed—78.6 million prescriptions were written in 2017 alone—and considered to be one of the safest drugs on the market for managing diabetes. Patients have been attracted to the extended release version in particular for its once-daily dosage, while the immediate release formulation must be taken twice a day. But even in the wake of the recall, pharmacy industry experts have commented that metformin should not be considered totally unsafe now. Rather, the FDA’s testing has indicated only certain lots of ERM were impacted. The current consensus points towards a flaw in the manufacturing process as the source of NDMA, though details of the contamination are still under investigation.

Detecting Danger Abroad

Prior to the FDA’s metformin recall announcements, other countries were already monitoring the drug’s safety. In 2019, the Health Sciences Authority of Singapore (HSA) discovered NDMA contamination in some types of metformin drugs. This led to a December 2019 recall of certain extended release tablets manufactured by Pharmazen Medicals Pte. Ltd. and Glorious Dexa Singapore.

In February 2020, Canadian officials announced recalls of certain lots of Apotex’s ERM tablets and six ERM lots from Ranbaxy Pharmaceuticals. The studies underlying these recalls prompted authorities in Europe and the U.S. to start looking into potential contamination in ERM products in their respective markets. However, an initial FDA study announced in February 2020 showed no instances where NDMA levels exceeded the acceptable daily intake limit of 96 nanograms.

But it was an NDMA discovery by a private laboratory company that caught the FDA’s attention. The Connecticut-based company, Valisure, observed more than 10 times the accepted level of NDMA in several tested batches of metformin. Further, researchers found there was significant batch to batch variability, even within a single company. Armed with these alarming results, Valisure then petitioned the FDA to take metformin off the U.S. market, leading to the eventual recall.

The Recall Process

The FDA recall addressed metformin makers, manufacturers, and patients. The makers named in the recall are Apotex Corp., Amneal Pharmaceuticals, Marksans Pharma Limited’s Time-Cap Labs, Inc., Lupin Pharmaceuticals Inc., and Teva Pharmaceuticals USA, Inc.’s Actavis Generics. The FDA’s announcement indicated that these five companies would be notifying wholesalers, distributors, and retailers to make arrangements for the return of the products.

The FDA also asked all companies—beyond the five named makers—that manufacture ERM to carefully monitor ongoing production and evaluate whether these products contain NDMA above the acceptable intake levels. The manufacturing companies must also test at-risk metformin lots before releasing a batch into the U.S. market. If the metformin testing indicates that NDMA is above the acceptable intake limit, the companies must inform the FDA and these batches must not be released in the market.

The FDA recommended that patients already using recalled ERM continue taking it “until a doctor or pharmacist gives them a replacement or a different treatment option.” This is meant avoid any adverse effects from a sudden stop in their metformin treatment. The FDA also urged health care professionals to prescribe ERM only when clinically appropriate, noting that testing has not found NDMA in immediate release metformin products, the most commonly prescribed type of metformin.

Pending Metformin Lawsuits

Already, lawsuits have emerged from patients potentially harmed by contaminated metformin. Metformin litigation will certainly continue to form from the millions of impacted Americans, especially after observing the surge of cases related to another NDMA-tainted drug: Zantac. Thus far, 230 Zantac claims have been consolidated in the Southern District Court of Florida and are moving into the discovery phase. Surely close behind Zantac, here are the cases already underway with metformin claims.

Class Action Against Granules USA

On March 20, 2020, an Indiana woman filed a class action on behalf of similarly situated consumers against Granules USA, Inc. and Granules Pharmaceuticals, Inc. The plaintiffs claim they were injured by paying the full purchase price for medications containing harmful levels of NDMA. The plaintiff seeks damages and restitution for a breach of the implied warranty of merchantability, unjust enrichment, fraudulent concealment, fraud, and conversion.

Healthcare Insurer Class Action

On April 3, 2020, healthcare insurer, MSP Recovery Claims, Series LLC filed a class action lawsuit on behalf of similarly-situated healthcare insurers. The suit, that names six separate pharmaceutical company defendants, seeks to recover millions of dollars in payments they allege were unlawfully solicited for contaminated metformin. The plaintiffs claim that the defendants concealed pervasive good manufacturing practice violations and defrauded the plaintiffs. The plaintiffs are demanding damages for breach of express and implied warranties, common law fraud, violations of the Florida Deceptive and Unfair Trade Practices Act, and unjust enrichment.

Expert Witnesses for Metformin Cases

Attorneys representing clients in metformin cases will rely heavily on expert witnesses for the technical aspects of alleged pharmaceutical manufacturing errors. Specialized experts in drug manufacturing processes will be needed early in a case to help attorneys understand foundational aspects of the metformin contamination. Attorneys must also consult oncology experts to understand how NDMA is linked to cancer development and the inherent health risks posed to patients. For these technical and high volume suits, experts will likely be deposed during discovery and quite possibly called to testify at trials. As these cases proceed, experts are sure to play crucial roles in assigning liability and assessing potential damages.


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